In forage harvesters, it is of interest to determine the given harvested material throughput, for the purpose of precision agriculture, automated metering of a silylation agents or accounting for contractors. For this purpose, various sensors have been proposed which measure the harvested material throughput, for example, on the basis of the separation between the upper and lower preliminary press rolls, the intensity of the radiation penetrating the harvested material stream, the power consumption of a chopper cylinder, or of a discharge accelerator arranged downstream of the chopper cylinder (Auernhammer at al., Yield Measurement on Self Propelled Forage Harvesters, ASAE Paper No. 951757). In practice, the throughput measurement using radiation has not been found to be acceptable, and the measurement of the separation between the preliminary press rolls is, on the one hand, relatively imprecise, particularly in the case of a feed channel that is filled non-homogeneously in the transverse direction, and, on the other hand, it also requires knowledge of the density of the harvested material, to evaluate the mass throughput which is considered to be particularly relevant. The disadvantages do not exist in the case of the determination of the drive moment of the discharge accelerator.
However, in forage harvesters, there is usually a kernel processor arranged, when viewed in the direction of harvested material flow, between the chopper cylinder and a discharge accelerator, which kernel processor is driven by the drive shaft of the discharge accelerator during corn harvesting to crack the kernels contained in the harvested material stream. For this purpose, the drive shaft of the discharge accelerator is driven on the side of the discharge accelerator by a belt pulley, against which a drive belt driven by the combustion engine of the forage harvester is applied, while, on the other side of the discharge accelerator, a belt pulley, mounted on the drive shaft, drives the kernel processor, via an additional drive belt (see DE 196 03 928 A1). A direct determination of the drive moment at the drive shaft is consequently not possible.
In EP 0 463 240 A1, a chaff conveyor in a combine harvester is described, which comprises paddles linked by springs to a shaft. On the basis of the angle of the paddles with respect to the shaft, the material throughput is determined with an optical sensor which in addition works in cooperation with a reference element attached rigidly to the shaft.